This invention relates to a container handling apparatus, and more particularly an apparatus incorporating a cradle adapted to be interconnected to a shipping container whereby the container can be shifted onto and off the trailer (tray) of a truck at a shipping port, rail terminal and/or factory.
Manipulation of containers is typically done by using forklift trucks, side-lifters, mobile cranes or accessories such as portable lifting devices in the form of jigs and jacks which can be located on-site or carried with a container.
Forklift trucks are very expensive equipment and are usually only available at well equipped sites, and are not necessarily available at many sites where containers need to be loaded onto and off the trays or trailers of road transports/trucks. Side-lifters are also only available at well equipped sites and due to their manner of operation require space equivalent to three times the width of the container. Mobile cranes on the other hand are also very costly installations and normally only available at sites dedicated to the handling of large numbers of containers, such as at a shipping port.
As an alternative to forklift trucks, side-lifters and mobile cranes, portable lifting devices have been proposed, and such a lifting device is disclosed in International patent publication WO92/19527. However, the weight of a fully loaded container with such lifting devices leads to instability when supported on a number of separate jacks at each corner of the container, and thus such devices are not a totally satisfactory solution to the problem of lifting and manoeuvring containers, whilst in addition, the lifting devices require the services of a forklift truck to position the devices for attachment to a container.
Other lifting devices that are known utilise a rigid chassis having a plurality of lifting jacks, and examples of these are disclosed in U.S. Pat. Nos. 3,460,697, 4,053,073, 3,520,433, 4,522,550 and 3,152,709. However, none of the disclosures in these publications provide a container handling system adapted to move a container, in particular the movement of a container once it has been elevated for loading onto transport. The ability to move containers small distances is a particularly important problem which has not been addressed by any of the prior art devices or systems presently available to handle containers. Furthermore, none of the known devices and systems are able to be attached to the top of the container such that a single container handling system or cradle can be used on multiple containers. An overhead crane can be used to fit such devices and systems to a container thereby avoiding the need for forklifts or other types of mobile cranes.
Therefore, problems associated with loading and unloading containers onto and off the trays or trucks is only satisfactorily accomplished at very well equipped sites by the use of sophisticated and highly costly dedicated equipment. Moveover, the ability to manipulate, that is, manoeuvre, containers small distances is only available with the use of the same equipment used for loading and unloading the containers.
It has been proposed in International patent publication no. WO94/26630, to provide a container handling apparatus incorporating a cradle adapted for attachment to the top or bottom of a container, and having a chassis adapted to enagagably receive a container unit and two or more lifting legs adapted for independent or coordinated movement to effect the controlled movement of a container fitted to the cradle in any required vertical or horizontal direction, wherein the chassis has a substantially rigid frame dimensioned to allow stable engagement with a container and the lifting legs comprise laterally extending members attached to the frame and adapted for controllable movement in a lateral direction away from or toward the frame with members attached to the lateral extending member and adapted for controlling movement in the direction substantially vertical to the plane of movement of the lateral extending member such as to combine controlled movement of the lateral extending members and the lifting members of the lifting legs of the cradle provide for the control of manipulation of the cradle and can engage a container in any required vertical or horizontal lateral direction.
However, the container handling apparatus of the disclosure in publication no. WO94/26630 is a static apparatus insofar as, although it can raise and lower a container, the tray of the truck has to be positioned beneath the container when elevated by backing the trailer into position beneath the container when loading or by driving the truck tray away from beneath the container when unloading.
It is therefore an object of the present invention to provide a container handling apparatus utilising a cradle having a chassis adapted specifically for attachment to the top of a shipping container and having lifting legs attached to each corner of the chassis and incorporating lifting rams, wherein the legs are pivotably attached at pivot points to the respective corners whereby to be swung between positions extending alongside said chassis in a stored orientation and positions extending downwardly from said chassis in a ground engaging orientation, and wherein the pivotable attachments for said lifting legs are such that the position of the legs can be extended and retracted laterally of said chassis, and wherein the lower ends of said legs carry wheels for mobility whereby said cradle with said legs extending downwardly from said chassis in a ground engaging orientation with, or without, a container suspended beneath said chassis, can be moved from one position to another.